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        </div><article class="page single"><h1 class="single-title animated flipInX">《Flutter开发Tip1》</h1><div class="post-meta">
            <div class="post-meta-line"><span class="post-author"><a href="/" title="Author" rel=" author" class="author"><i class="fas fa-user-circle fa-fw"></i>飞雪无情</a></span>&nbsp;<span class="post-category">included in <a href="/categories/Flutter/"><i class="far fa-folder fa-fw"></i>Flutter</a></span></div>
            <div class="post-meta-line"><i class="far fa-calendar-alt fa-fw"></i>&nbsp;<time datetime="2021-07-30">2021-07-30</time>&nbsp;<i class="fas fa-pencil-alt fa-fw"></i>&nbsp;437 words&nbsp;
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  <ul>
    <li><a href="#heading">…</a></li>
    <li><a href="#for-">for ()…[]</a></li>
    <li><a href="#--">() {} ()</a></li>
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            </div><div class="content" id="content"><blockquote>
<p>本文主要介绍flutter开发小技巧</p>
</blockquote>
<h2 id="heading">…</h2>
<p>延展操作符(<code>...</code>)可以对数组或者字典进行操作</p>
<pre><code>// 合并数组
test1() {
  var list = [1, 2, 3];
  var list2 = [0, ...list, 4];
  print(list2);
  // [0, 1, 2, 3, 4]
}

// 合并字典
test2() {
  var map1 = {
    &quot;key1&quot;: &quot;value1&quot;,
    &quot;key2&quot;: &quot;value2&quot;,
  };
  var map2 = {
    &quot;key3&quot;: &quot;value3&quot;,
    &quot;key4&quot;: &quot;value4&quot;,
  };
  var map3 = {...map1, ...map2};
  print(map3);
  // {key1: value1, key2: value2, key3: value3, key4: value4}
}
</code></pre><h2 id="for-">for ()…[]</h2>
<p>合并widgets到集合中，使用<code>for ()...[]</code>范式，使用延展操作符(<code>...</code>)来合并一个数组的widgets到一个存在的集合中。例如在构造Row或者Column的children时，非常方便。下面是示例：</p>
<pre><code>List&lt;Food&gt; foods = [
  Food(name: 'apple', isVegetarian: true),
  Food(name: 'nuts', isVegetarian: true),
  Food(name: 'eggs', isVegetarian: true),
  Food(name: 'chicken', isVegetarian: false),
];

class Food {
  Food({
    this.name,
    this.isVegetarian,
  });

  String name;
  bool isVegetarian;
}

class HomePage extends StatelessWidget {
  const HomePage({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        children: [
          Container(),
          for (final food in foods) ...[
            if (food.isVegetarian) ListTile(title: Text(food.name)),
            SizedBox(height: 50.0),
          ],
        ],
      ),
    );
  }
</code></pre><h2 id="--">() {} ()</h2>
<p>立即执行一个匿名函数：<code>() {} ()</code>,相当于声明一个匿名函数并且里面执行，这种范式在处理一个widget可能有多种输出时特别有用。而不是使用镶嵌的三目运算符或者通过一个函数调用，这个代码跟内联。下面是示例：</p>
<pre><code>T getRandomElement&lt;T&gt;(List&lt;T&gt; list) =&gt; list[Random().nextInt(list.length)];

Column(
          children: [
            Container(
              color: () {
                switch (getRandomElement(foods).name) {
                  case 'apple':
                    return Colors.green;
                  case 'nuts':
                    return Colors.brown;
                  case 'eggs':
                    return Colors.yellow;
                  default:
                    return Colors.transparent;
                }
              }(),
              child: Text('Food of the Day'),
            ),
          ],
        )
</code></pre></div><div class="post-footer" id="post-footer">
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